Processes are currently developed in the world practice of steelmaking that use the direct alloying process wherein nonmetal compounds containing an alloying element are used as alloying, modifying additives supplied into metallurgical units with a reducing agent in series or jointly, or in the form of mixtures or briquettes. One of important moments in the direct alloying technology is synchronization of the processes of melting materials to be supplied, reducing alloying elements, and deoxidizing steel. For this purpose, raw materials are supplied in such an order and in such ratios that their melting takes place simultaneously, practically at the same rate. Such supplying provides forming of a homogeneous phase consisting of materials that participate in the reduction process. Accordingly, the reaction of reducing the alloying elements begins and goes simultaneously with the melting process and provides thereby a high rate and completeness of the reduction process.
Taking into account that the requirements to the quality of steel currently increase practically throughout its entire range, the necessity occurs to perform additional procedures, particularly, steel micro-alloying and steel modifying. Combining of the processes of steel alloying and steel modifying seems impossible by using of the existing equipment for supplying necessary materials. According to the existing technologies, the alloying and modifying processes are carried out separately: the alloying takes place in a steel-teeming ladle during discharge of a metal while the micro-alloying and modifying take place in the out-of-furnace treatment installations. This implies the necessity to use additional equipment in the form of injection installations, tribe-apparatuses and others, overheat of metal prior to discharge or in ladle furnace installations; apart from increase in energetic and material costs, this results in prolongation of the melting cycle.
To realize both the steelmaking processes using the direct alloying and the possibility to combine the alloying and modifying processes, is it necessary to use systems for supplying materials into a metallurgical unit that permits the supply of necessary materials at a controllable rate, mass, sequence. The steelmaking processes using the direct alloying and the possibility to combine the alloying and modifying processes have required to solve the question of creating such an apparatus that could provide the supply of a strictly regulated amount of necessary materials according to predetermined programs and sequence of supplying thereof.
Known is an installation for supplying materials into a metallurgical unit (a steelmelting unit and a ladle), comprising storage hoppers for slag-forming materials, carbonaceous materials, and oxidized materials, hoppers for storing deoxidizing agents and alloying agents, a system for supplying material into the steelmaking unit, said system including screens and electro-vibrating feeders, weighting batchers, intermediate hoppers with gates and mounted above the steelmaking unit, all being positioned in a technological sequence, and systems for supplying materials into the steel-teeming ladle, said systems including electro-vibrating feeders, weighting batchers and charge funnels with pipe-chutes, all being positioned in a technological sequence (Arist, L. M., Shcherbin, A. I., “Mekhanizatsia Rabot v Domennom i Staleplavil'nom Proizvodstvakh” (Mechanization of Works in Blast-Furnace and Steelmaking Plants)—K.: Tekhinka (The Engineering Publishers), 1991, pp. 48-49).
It seems impossible to implement the steel alloying and modifying processes using the direct steel alloying process in such an installation, because the structural embodiment of the installation does not provide the timely supply of all materials necessary for direct alloying, that is, nonmetallic materials containing alloying elements, reducing agents and slag-forming materials, into the steelmaking unit or into the steel-teeming ladle.
Known is a continuous production line for preparing and supplying slag-forming mixtures into a steelmaking unit and ladle, comprising receiving hoppers with gates, weighting batchers, collecting hoppers coupled to each other by conveyors with discharge mechanisms and chutes, all being mounted according to the course of the manufacturing process, wherein the receiving hoppers are made with inclined chutes fastened under the gates and the continuous production line is provided with continuous weighting devices, material-overflow chutes, a combined tank connected to an aspiration system, said continuous weighting devices being fastened under the included chutes of the receiving hoppers and made by-pair-integrated into the combined tank while the material-overflow chutes being mounted so as to change a direction of supplying material from a charge path of the steelmaking unit into a system for inlet into the ladle (RU 2,010,865 C1, IPC C21C 7/00, 1994).
Employment of the prior art installation covers only the supply of two materials into the steelmaking unit or into the steel-teeming ladle. Said materials are slag-forming materials—lime and fluor-spar.
The known installation solves a practical problem of preparing the mixture of slag-forming materials comprising only two materials—lime and fluor-spar.
At least three materials should be used as raw materials in the technology of steel alloying with any alloying elements: a material containing an alloying element, a reducing agent, and a slag-forming additive.
In accordance with the solution of RU 2,010,865, the prepared mixture of the slag-forming materials—lime and fluor-spar in the predetermined fixed ratio equal to 4:1—is supplied into one combined tank from which the finished mixture is directed through respective chutes into the steelmaking unit or into the steel-teeming ladle.
Use of the prior art installation does not provide the required mode of regulated supplying materials necessary for direct steel alloying because the regulated and timely supply of all materials is not provided as well as the required operation speed in supply of materials into the steelmaking unit or into the steel-teeming ladle.
Because of necessity to supply materials in the direct alloying technology according to a predetermined, always strictly preset sequence and not in the form a mixture of all supplied materials, wherein said necessity being connected with different times of melting the supplied materials, it is inexpedient to use the prior art installation since this results in violation of the preset technological regulations and impossibility to implement the process of direct steel alloying.
Known is an installation for supplying material into a steelmaking furnace and into a steel-teeming ladle, mounted in the prior art continuous production line for supplying materials by electric-furnace steelmaking, comprising a distributing device made as a multi-section funnel with a swivel launder and a drive thereof, wherein sections of the funnel are connected by direct-flow chutes for supplying materials into the steelmaking furnace and into the steel-teeming ladle and by functionally-independent chutes for supplying materials during treatment of steel in ladles under which intermediate hoppers are mounted with feeders at bases of which hopper scales for small dozes are positioned under which the funnel is fastened, and a flow divider (SU 1,020,442, IPC C21C 7/00, published on May 30, 1983).
It seems impossible to accomplish the operation speed in supply of necessary materials for direct steel alloying with the controllable supply sequence and rate using the prior art installation, because all necessary materials are supplied according to the prior art invention from one tank—the hopper scale for small dozes at which the necessary materials arrive through the feeders from the intermediate hoppers. Therefore, by supplying, for example, of three materials, it is necessary to supply all necessary materials in series to the hopper scale and supply them already as a mixture into the steelmaking unit or into ladle, which is unacceptable for the technology of direct steel alloying where materials are supplied advantageously separately, or in turn. This leads to breakdown in the manufacturing process of direct alloying that provides the supply of necessary materials in a strict sequence and at compliance with the necessary regulations.
With such a structural embodiment of supplying the necessary materials from the intermediate hoppers into the steelmaking unit or ladle, it seems impossible to implement synchronism of processes taking place by direct steel alloying, first of all, because of violating the mode of independent supplying necessary materials as well as violating the technological regulations of direct steel alloying in process of operation of the installation.